Hello Markus,
If you loosen the screw(on a reference or DPS arm) and retighten it, you'd only have to adjust for Zenith again. Not overhang, nor azimuth or tracking force will be affected.
With the No. 2 and the Clearaudio Unify(their headshell is a copy), both overhang, zenith and, to a small degree, VTF need to be checked at the same time, true for any headshell with slots and a touch of "slack"(in regards to the diameter of the cartridge screws).
Personally I know quite a few dealers who find my arms easy to set up. But which dealer sets up the arm for his customers any more. Not many...
All the best,
Frank Schröder